A subscriber identity module (Subscriber Identity Module, SIM) card applied in an existing Global System of Mobile Communications (Global System of Mobile Communications, GSM) is also called a smart card, a subscriber identity card, or the like. A SIM card is generally a chip, which can be disposed inside a mobile terminal, and is used to store content of the mobile terminal, such as subscriber information, an cipher key, and a user phonebook, and is provided for a GSM network to authenticate an identity of a subscriber and encrypt voice information during a call of the subscriber, and the like.
A SIM card in the prior art is generally a chip provided with a microprocessor and a hardware structure. When a user carrying a terminal roams between different regions, the user usually chooses to use a SIM card registered in a roamed-to region in order to reduce roaming charges. Because a SIM card in the prior art is a chip provided with a hardware structure, when the SIM card is replaced, the user needs to insert another SIM card into a reserved position of the terminal. When roaming between different regions, the user needs to replace the SIM card frequently, which causes inconvenience of use and affects user experience.